A surge arrester of the above-mentioned kind is previously known from U.S. Pat. No. 4,262,318. In this surge arrester a plurality of surge arrester elements in the form of zinc oxide varistors are arranged in a stack and enclosed within a housing of porcelain with a gap between the housing and the varistor stack. In the event of a fault inside the surge arrester with a resultant short-circuit current and violent gas development, a high pressure may be built up in the above-mentioned gap. In such a design, therefore, special and often expensive measures for pressure relief have to be taken so that the housing does not burst in an uncomfortable manner, causing secondary damage by splinters being thrown out. Other drawbacks in connection with this design are that it requires a relatively large space and that only a limited number of parallel varistor stacks can be accomodated within one and the same porcelain housing.
Also a surge arrester in which the arrester elements are provided with a tightly surrounding housing of a shrinkable plastic or rubber material is previously known (GB-A-2 073 965). As mechanical reinforcement of this surge arrester it has been proposed to arrange an insulating rod between the end fittings of the surge arrester. This rod extends through an axial hole in the sruge arrester elements. Such a design presupposes a gas-tight housing which shields the rod from the outside environment, since there is otherwise a risk of creeping currents whcih may cause a flash-over in the gap which is inevitably formed between the rod and the hole wall. For higher voltages this surge arrester is less suitable.